buffer-file-truename is an *abbreviated* truename, so use file-truename instead.
buffer-file-truename is an *abbreviated* truename, so use file-truename instead.

Closes gh-19

gorakhargosh/go-mode.el,emacsmirror/go-mode,tjyang/go-mode.el,magastzheng/go-mode.el,ibukanov/go-mode.el,kimiby/go-mode.el,codemac/go-mode.el,dominikh/go-mode.el,artemave/go-mode.el